Definición de compatibilidad con Android 2.3

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compatibilidad@android.com

Tabla de contenido

1. Introducción

Este documento enumera los requisitos que se deben cumplir para que los teléfonos móviles sean compatibles con Android 2.3.

El uso de "debe", "no debe", "obligatorio", "deberá", "no deberá", "debería", "no debería", "recomendado", "puede" y "opcional" se ajusta al estándar del IETF. definido en RFC2119 [ Recursos, 1 ].

Tal como se utiliza en este documento, un "implementador de dispositivos" o "implementador" es una persona u organización que desarrolla una solución de hardware/software que ejecuta Android 2.3. Una "implementación de dispositivo" o "implementación" es la solución de hardware/software así desarrollada.

Para ser considerado compatible con Android 2.3, las implementaciones de dispositivos DEBEN cumplir con los requisitos presentados en esta Definición de compatibilidad, incluido cualquier documento incorporado mediante referencia.

Cuando esta definición o las pruebas de software descritas en la Sección 10 no dicen nada, son ambiguas o están incompletas, es responsabilidad del implementador del dispositivo garantizar la compatibilidad con las implementaciones existentes. Por esta razón, el Proyecto de código abierto de Android [ Recursos, 3 ] es la implementación de referencia y preferida de Android. Se recomienda encarecidamente a los implementadores de dispositivos que basen sus implementaciones en la mayor medida posible en el código fuente "ascendente" disponible en el Proyecto de código abierto de Android. Si bien hipotéticamente algunos componentes pueden reemplazarse con implementaciones alternativas, se desaconseja encarecidamente esta práctica, ya que pasar las pruebas de software será sustancialmente más difícil. Es responsabilidad del implementador garantizar la compatibilidad total del comportamiento con la implementación estándar de Android, incluido y más allá del Compatibility Test Suite. Finalmente, tenga en cuenta que este documento prohíbe explícitamente ciertas sustituciones y modificaciones de componentes.

Tenga en cuenta que esta Definición de compatibilidad se emite para corresponder con la actualización 2.3.3 de Android, que es el nivel de API 10. Esta Definición obsoleta y reemplaza la Definición de compatibilidad para las versiones de Android 2.3 anteriores a la 2.3.3. (Es decir, las versiones 2.3.1 y 2.3.2 están obsoletas). Los futuros dispositivos compatibles con Android que ejecuten Android 2.3 DEBEN enviarse con la versión 2.3.3 o posterior.

2. Recursos

1. Niveles de requisitos IETF RFC2119: http://www.ietf.org/rfc/rfc2119.txt
2. Descripción general del programa de compatibilidad de Android: http://source.android.com/docs/compatibility/index.html
3. Proyecto de código abierto de Android: http://source.android.com/
4. Definiciones y documentación de API: http://developer.android.com/reference/packages.html
5. Referencia de permisos de Android: http://developer.android.com/reference/android/Manifest.permission.html
6. Referencia de android.os.Build: http://developer.android.com/reference/android/os/Build.html
7. Cadenas de versión permitidas de Android 2.3: http://source.android.com/docs/compatibility/2.3/versions.html
8. Clase android.webkit.WebView: http://developer.android.com/reference/android/webkit/WebView.html
9. HTML5: http://www.whatwg.org/specs/web-apps/current-work/multipage/
10. Capacidades HTML5 sin conexión: http://dev.w3.org/html5/spec/Overview.html#offline
11. Etiqueta de vídeo HTML5: http://dev.w3.org/html5/spec/Overview.html#video
12. API de geolocalización HTML5/W3C: http://www.w3.org/TR/geolocation-API/
13. API de base de datos web HTML5/W3C: http://www.w3.org/TR/webdatabase/
14. API HTML5/W3C IndexedDB: http://www.w3.org/TR/IndexedDB/
15. Especificación de la máquina virtual Dalvik: disponible en el código fuente de Android, en dalvik/docs
16. AppWidgets: http://developer.android.com/guide/practices/ui_guidelines/widget_design.html
17. Notificaciones: http://developer.android.com/guide/topics/ui/notifiers/notifications.html
18. Recursos de la aplicación: http://code.google.com/android/reference/available-resources.html
19. Guía de estilo de iconos de la barra de estado: http://developer.android.com/guide/practices/ui_guideline /icon_design.html#statusbarstructure
20. Administrador de búsqueda: http://developer.android.com/reference/android/app/SearchManager.html
21. Brindis: http://developer.android.com/reference/android/widget/Toast.html
22. Fondos de pantalla en vivo: https://android-developers.googleblog.com/2010/02/live-wallpapers.html
23. Documentación de la herramienta de referencia (para adb, aapt, ddms): http://developer.android.com/guide/developing/tools/index.html
24. Descripción del archivo apk de Android: http://developer.android.com/guide/topics/fundamentals.html
25. Archivos de manifiesto: http://developer.android.com/guide/topics/manifest/manifest-intro.html
26. Herramienta de prueba de monos: https://developer.android.com/studio/test/other-testing-tools/monkey
27. Lista de funciones de hardware de Android: http://developer.android.com/reference/android/content/pm/PackageManager.html
28. Compatible con varias pantallas: http://developer.android.com/guide/practices/screens_support.html
29. android.util.DisplayMetrics: http://developer.android.com/reference/android/util/DisplayMetrics.html
30. android.content.res.Configuration: http://developer.android.com/reference/android/content/res/Configuration.html
31. Espacio de coordenadas del sensor: http://developer.android.com/reference/android/hardware/SensorEvent.html
32. API de Bluetooth: http://developer.android.com/reference/android/bluetooth/package-summary.html
33. Protocolo push NDEF: http://source.android.com/docs/compatibility/ndef-push-protocol.pdf
34. MIFARE MF1S503X: http://www.nxp.com/documents/data_sheet/MF1S503x.pdf
35. MIFARE MF1S703X: http://www.nxp.com/documents/data_sheet/MF1S703x.pdf
36. MIFARE MF0ICU1: http://www.nxp.com/documents/data_sheet/MF0ICU1.pdf
37. MIFARE MF0ICU2: http://www.nxp.com/documents/short_data_sheet/MF0ICU2_SDS.pdf
38. MIFARE AN130511: http://www.nxp.com/documents/application_note/AN130511.pdf
39. MIFARE AN130411: http://www.nxp.com/documents/application_note/AN130411.pdf
40. API de orientación de la cámara: http://developer.android.com/reference/android/hardware/Camera.html#setDisplayOrientation(int)
41. android.hardware.Camera: http://developer.android.com/reference/android/hardware/Camera.html
42. Referencia de permisos y seguridad de Android: http://developer.android.com/guide/topics/security/security.html
43. Aplicaciones para Android: http://code.google.com/p/apps-for-android

Muchos de estos recursos se derivan directa o indirectamente del SDK de Android 2.3 y serán funcionalmente idénticos a la información contenida en la documentación de ese SDK. En cualquier caso en el que esta Definición de compatibilidad o el Conjunto de pruebas de compatibilidad no estén de acuerdo con la documentación del SDK, la documentación del SDK se considera autorizada. Cualquier detalle técnico proporcionado en las referencias incluidas anteriormente se considera por inclusión parte de esta Definición de compatibilidad.

3.software

La plataforma Android incluye un conjunto de API administradas, un conjunto de API nativas y un conjunto de API denominadas "blandas", como el sistema Intent y las API de aplicaciones web. Esta sección detalla las API físicas y blandas que son parte integral de la compatibilidad, así como otros comportamientos técnicos y de interfaz de usuario relevantes. Las implementaciones de dispositivos DEBEN cumplir con todos los requisitos de esta sección.

3.1. Compatibilidad de API administrada

El entorno de ejecución administrado (basado en Dalvik) es el vehículo principal para las aplicaciones de Android. La interfaz de programación de aplicaciones (API) de Android es el conjunto de interfaces de la plataforma Android expuestas a aplicaciones que se ejecutan en el entorno de VM administrado. Las implementaciones de dispositivos DEBEN proporcionar implementaciones completas, incluidos todos los comportamientos documentados, de cualquier API documentada expuesta por el SDK de Android 2.3 [ Recursos, 4 ].

Las implementaciones de dispositivos NO DEBEN omitir ninguna API administrada, alterar las interfaces o firmas de API, desviarse del comportamiento documentado ni incluir operaciones no operativas, excepto donde lo permita específicamente esta Definición de compatibilidad.

Esta Definición de compatibilidad permite que las implementaciones de dispositivos omitan algunos tipos de hardware para los cuales Android incluye API. En tales casos, las API DEBEN seguir estando presentes y comportarse de forma razonable. Consulte la Sección 7 para conocer los requisitos específicos para este escenario.

3.2. Compatibilidad de API suave

Además de las API administradas de la Sección 3.1, Android también incluye una importante API "suave" solo en tiempo de ejecución, en forma de elementos como intenciones, permisos y aspectos similares de las aplicaciones de Android que no se pueden aplicar en el momento de la compilación de la aplicación. Esta sección detalla las API "soft" y los comportamientos del sistema necesarios para la compatibilidad con Android 2.3. Las implementaciones de dispositivos DEBEN cumplir con todos los requisitos presentados en esta sección.

3.2.1. Permisos

Los implementadores de dispositivos DEBEN admitir y hacer cumplir todas las constantes de permisos según lo documentado en la página de referencia de permisos [ Recursos, 5 ]. Tenga en cuenta que la Sección 10 enumera requisitos adicionales relacionados con el modelo de seguridad de Android.

3.2.2. Parámetros de construcción

Las API de Android incluyen una serie de constantes en la clase android.os.Build [ Recursos, 6 ] que están destinadas a describir el dispositivo actual. Para proporcionar valores coherentes y significativos en todas las implementaciones de dispositivos, la siguiente tabla incluye restricciones adicionales sobre los formatos de estos valores a los que DEBEN ajustarse las implementaciones de dispositivos.

3.2.3. Compatibilidad de intenciones

Android usa Intents para lograr una integración débil entre aplicaciones. Esta sección describe los requisitos relacionados con los patrones de intención que DEBEN ser respetados por las implementaciones de dispositivos. Por "honrado" se entiende que el implementador del dispositivo DEBE proporcionar una Actividad o Servicio de Android que especifique un filtro de Intención coincidente y se vincule e implemente el comportamiento correcto para cada patrón de Intención especificado.

3.2.3.1. Intenciones principales de la aplicación

El proyecto upstream de Android define una serie de aplicaciones principales, como un marcador telefónico, un calendario, una libreta de contactos, un reproductor de música, etc. Los implementadores de dispositivos PUEDEN reemplazar estas aplicaciones con versiones alternativas.

Sin embargo, cualquiera de estas versiones alternativas DEBE respetar los mismos patrones de intención proporcionados por el proyecto inicial. Por ejemplo, si un dispositivo contiene un reproductor de música alternativo, aún debe respetar el patrón de intención emitido por aplicaciones de terceros para elegir una canción.

Las siguientes aplicaciones se consideran aplicaciones principales del sistema Android:

• Reloj de escritorio
• Navegador
• Calendario
• Calculadora
• Contactos
• Correo electrónico
• Galería
• Búsqueda global
• Lanzacohetes
• Música
• Ajustes

Las aplicaciones principales del sistema Android incluyen varios componentes de Actividad o Servicio que se consideran "públicos". Es decir, el atributo "android:exportado" puede estar ausente o puede tener el valor "verdadero".

Para cada Actividad o Servicio definido en una de las aplicaciones principales del sistema Android que no esté marcado como no público mediante un atributo android:exportado con el valor "falso", las implementaciones del dispositivo DEBEN incluir un componente del mismo tipo que implemente el mismo filtro de Intención. patrones como la aplicación principal del sistema Android.

En otras palabras, la implementación de un dispositivo PUEDE reemplazar las aplicaciones principales del sistema Android; sin embargo, si es así, la implementación del dispositivo DEBE admitir todos los patrones de intención definidos por cada aplicación principal del sistema Android que se reemplaza.

3.2.3.2. Anulaciones de intención

Como Android es una plataforma extensible, los implementadores de dispositivos DEBEN permitir que cada patrón de Intención al que se hace referencia en la Sección 3.2.3.1 sea anulado por aplicaciones de terceros. El proyecto de código abierto de Android permite esto de forma predeterminada; Los implementadores de dispositivos NO DEBEN otorgar privilegios especiales al uso de estos patrones de Intent por parte de las aplicaciones del sistema, ni evitar que aplicaciones de terceros se vinculen y asuman el control de estos patrones. Esta prohibición incluye específicamente, entre otras, la desactivación de la interfaz de usuario "Selector", que permite al usuario seleccionar entre múltiples aplicaciones que manejan el mismo patrón de intención.

3.2.3.3. Espacios de nombres de intención

Los implementadores de dispositivos NO DEBEN incluir ningún componente de Android que respete cualquier nuevo patrón de Intención o Intención de transmisión utilizando una ACCIÓN, CATEGORÍA u otra cadena clave en el espacio de nombres android.*. Los implementadores de dispositivos NO DEBEN incluir ningún componente de Android que respete cualquier nuevo patrón de Intención o Intención de transmisión utilizando una ACCIÓN, CATEGORÍA u otra cadena clave en un espacio de paquete que pertenece a otra organización. Los implementadores de dispositivos NO DEBEN alterar ni ampliar ninguno de los patrones de Intención utilizados por las aplicaciones principales enumeradas en la Sección 3.2.3.1.

Esta prohibición es análoga a la especificada para las clases de lenguaje Java en la Sección 3.6.

3.2.3.4. Intenciones de transmisión

Las aplicaciones de terceros dependen de la plataforma para transmitir ciertos Intents y notificarles sobre cambios en el entorno de hardware o software. Los dispositivos compatibles con Android DEBEN transmitir los Intents de transmisión pública en respuesta a los eventos apropiados del sistema. Las intenciones de transmisión se describen en la documentación del SDK.

3.3. Compatibilidad API nativa

El código administrado que se ejecuta en Dalvik puede llamar al código nativo proporcionado en el archivo .apk de la aplicación como un archivo ELF .so compilado para la arquitectura de hardware del dispositivo adecuada. Como el código nativo depende en gran medida de la tecnología del procesador subyacente, Android define una serie de interfaces binarias de aplicaciones (ABI) en el NDK de Android, en el archivo docs/CPU-ARCH-ABIS.txt . Si la implementación de un dispositivo es compatible con una o más ABI definidas, DEBE implementar la compatibilidad con el NDK de Android, como se muestra a continuación.

Si la implementación de un dispositivo incluye soporte para una ABI de Android,:

• DEBE incluir soporte para el código que se ejecuta en el entorno administrado para llamar al código nativo, utilizando la semántica estándar de la interfaz nativa de Java (JNI).
• DEBE ser compatible con el código fuente (es decir, compatible con el encabezado) y con los binarios (para ABI) con cada biblioteca requerida en la lista siguiente
• DEBE informar con precisión la interfaz binaria de aplicación (ABI) nativa admitida por el dispositivo, a través de la API android.os.Build.CPU_ABI
• DEBE informar solo aquellas ABI documentadas en la última versión del NDK de Android, en el archivo docs/CPU-ARCH-ABIS.txt
• DEBE construirse utilizando el código fuente y los archivos de encabezado disponibles en el proyecto de código abierto de Android.

Las siguientes API de código nativo DEBEN estar disponibles para aplicaciones que incluyen código nativo:

• libc (biblioteca C)
• libm (biblioteca de matemáticas)
• Soporte mínimo para C++
• interfaz JNI
• liblog (registro de Android)
• libz (compresión Zlib)
• libdl (enlazador dinámico)
• libGLESv1_CM.so (OpenGL ES 1.0)
• libGLESv2.so (OpenGL ES 2.0)
• libEGL.so (gestión de superficie nativa OpenGL)
• libjnigraphics.so
• libOpenSLES.so (soporte de audio de Open Sound Library)
• libandroid.so (soporte de actividad nativo de Android)
• Soporte para OpenGL, como se describe a continuación

Tenga en cuenta que las versiones futuras del NDK de Android pueden incluir compatibilidad con ABI adicionales. Si la implementación de un dispositivo no es compatible con una ABI predefinida existente, NO DEBE informar soporte para ninguna ABI en absoluto.

La compatibilidad del código nativo es un desafío. Por esta razón, se debe repetir que se recomienda MUY fuertemente a los implementadores de dispositivos que utilicen las implementaciones ascendentes de las bibliotecas enumeradas anteriormente para ayudar a garantizar la compatibilidad.

3.4. Compatibilidad web

Muchos desarrolladores y aplicaciones dependen del comportamiento de la clase android.webkit.WebView [ Recursos, 8 ] para sus interfaces de usuario, por lo que la implementación de WebView debe ser compatible con todas las implementaciones de Android. De manera similar, un navegador web completo y moderno es fundamental para la experiencia del usuario de Android. Las implementaciones de dispositivos DEBEN incluir una versión de android.webkit.WebView coherente con el software de Android anterior y DEBEN incluir un navegador moderno compatible con HTML5, como se describe a continuación.

3.4.1. Compatibilidad con WebView

La implementación de Android Open Source utiliza el motor de renderizado WebKit para implementar android.webkit.WebView . Debido a que no es factible desarrollar un conjunto de pruebas integral para un sistema de renderizado web, los implementadores de dispositivos DEBEN usar la compilación ascendente específica de WebKit en la implementación de WebView. Específicamente:

• Las implementaciones de android.webkit.WebView de las implementaciones de dispositivos DEBEN basarse en la compilación WebKit 533.1 del árbol de código abierto de Android ascendente para Android 2.3. Esta compilación incluye un conjunto específico de funcionalidades y correcciones de seguridad para WebView. Los implementadores de dispositivos PUEDEN incluir personalizaciones en la implementación de WebKit; sin embargo, dichas personalizaciones NO DEBEN alterar el comportamiento de WebView, incluido el comportamiento de representación.
• La cadena del agente de usuario informada por WebView DEBE tener este formato:
  Mozilla/5.0 (Linux; U; Android $(VERSION); $(LOCALE); $(MODEL) Build/$(BUILD)) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1
  • El valor de la cadena $(VERSION) DEBE ser el mismo que el valor de android.os.Build.VERSION.RELEASE
  • El valor de la cadena $(LOCALE) DEBE seguir las convenciones ISO para el código de país y el idioma, y ​​DEBE hacer referencia a la configuración regional actual del dispositivo.
  • El valor de la cadena $(MODEL) DEBE ser el mismo que el valor de android.os.Build.MODEL
  • El valor de la cadena $(BUILD) DEBE ser el mismo que el valor de android.os.Build.ID

El componente WebView DEBE incluir soporte para la mayor cantidad de HTML5 [ Recursos, 9 ] posible. Como mínimo, las implementaciones de dispositivos DEBEN admitir cada una de estas API asociadas con HTML5 en WebView:

• caché de aplicaciones/operación sin conexión [ Recursos, 10 ]
• la etiqueta <video> [ Recursos, 11 ]
• geolocalización [ Recursos, 12 ]

Además, las implementaciones de dispositivos DEBEN admitir la API de almacenamiento web HTML5/W3C [ Recursos, 13 ], y DEBEN admitir la API IndexedDB HTML5/W3C [ Recursos, 14 ]. Tenga en cuenta que a medida que los organismos de estándares de desarrollo web están haciendo la transición para favorecer IndexedDB sobre el almacenamiento web, se espera que IndexedDB se convierta en un componente requerido en una versión futura de Android.

Las API HTML5, como todas las API de JavaScript, DEBEN estar deshabilitadas de forma predeterminada en un WebView, a menos que el desarrollador las habilite explícitamente a través de las API habituales de Android.

3.4.2. Compatibilidad del navegador

Las implementaciones de dispositivos DEBEN incluir una aplicación de navegador independiente para la navegación web del usuario general. El navegador independiente PUEDE basarse en una tecnología de navegador distinta de WebKit. Sin embargo, incluso si se utiliza una aplicación de navegador alternativa, el componente android.webkit.WebView proporcionado a aplicaciones de terceros DEBE estar basado en WebKit, como se describe en la Sección 3.4.1.

Las implementaciones PUEDEN incluir una cadena de agente de usuario personalizada en la aplicación de navegador independiente.

La aplicación de navegador independiente (ya sea basada en la aplicación de navegador WebKit anterior o en un reemplazo de terceros) DEBE incluir soporte para la mayor cantidad de HTML5 [ Recursos, 9 ] posible. Como mínimo, las implementaciones de dispositivos DEBEN admitir cada una de estas API asociadas con HTML5:

• caché de aplicaciones/operación sin conexión [ Recursos, 10 ]
• la etiqueta <video> [ Recursos, 11 ]
• geolocalización [ Recursos, 12 ]

Además, las implementaciones de dispositivos DEBEN admitir la API de almacenamiento web HTML5/W3C [ Recursos, 13 ], y DEBEN admitir la API IndexedDB HTML5/W3C [ Recursos, 14 ]. Tenga en cuenta que a medida que los organismos de estándares de desarrollo web están haciendo la transición para favorecer IndexedDB sobre el almacenamiento web, se espera que IndexedDB se convierta en un componente requerido en una versión futura de Android.

3.5. Compatibilidad de comportamiento de API

Los comportamientos de cada uno de los tipos de API (administrada, suave, nativa y web) deben ser consistentes con la implementación preferida del proyecto de código abierto de Android [ Recursos, 3 ]. Algunas áreas específicas de compatibilidad son:

• Los dispositivos NO DEBEN cambiar el comportamiento o la semántica de un Intent estándar
• Los dispositivos NO DEBEN alterar el ciclo de vida o la semántica del ciclo de vida de un tipo particular de componente del sistema (como Servicio, Actividad, Proveedor de contenido, etc.)
• Los dispositivos NO DEBEN cambiar la semántica de un permiso estándar

La lista anterior no es exhaustiva. El Compatibility Test Suite (CTS) prueba partes importantes de la plataforma para determinar la compatibilidad del comportamiento, pero no todas. Es responsabilidad del implementador garantizar la compatibilidad del comportamiento con el Proyecto de código abierto de Android. Por esta razón, los implementadores de dispositivos DEBEN utilizar el código fuente disponible a través del Proyecto de código abierto de Android siempre que sea posible, en lugar de volver a implementar partes importantes del sistema.

3.6. Espacios de nombres API

Android sigue las convenciones de espacio de nombres de paquetes y clases definidas por el lenguaje de programación Java. Para garantizar la compatibilidad con aplicaciones de terceros, los implementadores de dispositivos NO DEBEN realizar modificaciones prohibidas (ver a continuación) en estos espacios de nombres de paquetes:

• Java.*
• javax.*
• sol.*
• androide.*
• com.android.*

Las modificaciones prohibidas incluyen:

• Las implementaciones de dispositivos NO DEBEN modificar las API expuestas públicamente en la plataforma Android cambiando cualquier método o firma de clase, o eliminando clases o campos de clase.
• Los implementadores de dispositivos PUEDEN modificar la implementación subyacente de las API, pero dichas modificaciones NO DEBEN afectar el comportamiento declarado ni la firma en lenguaje Java de las API expuestas públicamente.
• Los implementadores de dispositivos NO DEBEN agregar ningún elemento expuesto públicamente (como clases o interfaces, o campos o métodos a clases o interfaces existentes) a las API anteriores.

Un "elemento expuesto públicamente" es cualquier construcción que no esté decorada con el marcador "@hide" como se usa en el código fuente de Android. En otras palabras, los implementadores de dispositivos NO DEBEN exponer nuevas API ni alterar las API existentes en los espacios de nombres mencionados anteriormente. Los implementadores de dispositivos PUEDEN realizar modificaciones solo internas, pero esas modificaciones NO DEBEN publicitarse ni exponerse de otro modo a los desarrolladores.

Los implementadores de dispositivos PUEDEN agregar API personalizadas, pero dichas API NO DEBEN estar en un espacio de nombres que sea propiedad de otra organización o que haga referencia a ella. Por ejemplo, los implementadores de dispositivos NO DEBEN agregar API al com.google.* o espacio de nombres similar; sólo Google puede hacerlo. De manera similar, Google NO DEBE agregar API a los espacios de nombres de otras empresas. Además, si la implementación de un dispositivo incluye API personalizadas fuera del espacio de nombres estándar de Android, esas API DEBEN estar empaquetadas en una biblioteca compartida de Android para que solo las aplicaciones que las usan explícitamente (a través del mecanismo <uses-library> ) se vean afectadas por el mayor uso de memoria. de dichas API.

Si un implementador de dispositivo propone mejorar uno de los espacios de nombres de paquetes anteriores (por ejemplo, agregando nuevas funciones útiles a una API existente o agregando una nueva API), el implementador DEBE visitar source.android.com y comenzar el proceso para contribuir con cambios y código, según la información de ese sitio.

Tenga en cuenta que las restricciones anteriores corresponden a convenciones estándar para nombrar API en el lenguaje de programación Java; Esta sección simplemente tiene como objetivo reforzar esas convenciones y hacerlas vinculantes mediante su inclusión en esta definición de compatibilidad.

3.7. Compatibilidad de máquinas virtuales

Las implementaciones de dispositivos DEBEN admitir la especificación completa del código de bytes Dalvik Executable (DEX) y la semántica de la máquina virtual Dalvik [ Recursos, 15 ].

Las implementaciones de dispositivos con pantallas clasificadas como de densidad media o baja DEBEN configurar Dalvik para asignar al menos 16 MB de memoria a cada aplicación. Las implementaciones de dispositivos con pantallas clasificadas como de alta densidad o de densidad extra alta DEBEN configurar Dalvik para asignar al menos 24 MB de memoria a cada aplicación. Tenga en cuenta que las implementaciones de dispositivos PUEDEN asignar más memoria que estas cifras.

3.8. Compatibilidad de la interfaz de usuario

La plataforma Android incluye algunas API para desarrolladores que les permiten conectarse a la interfaz de usuario del sistema. Las implementaciones de dispositivos DEBEN incorporar estas API de UI estándar en interfaces de usuario personalizadas que desarrollen, como se explica a continuación.

3.8.1. widgets

Android define un tipo de componente y la API y el ciclo de vida correspondientes que permiten a las aplicaciones exponer un "AppWidget" al usuario final [ Recursos, 16 ]. La versión de referencia de Android Open Source incluye una aplicación de inicio que incluye elementos de interfaz de usuario que permiten al usuario agregar, ver y eliminar AppWidgets de la pantalla de inicio.

Los implementadores de dispositivos PUEDEN sustituir una alternativa al Iniciador de referencia (es decir, la pantalla de inicio). Los lanzadores alternativos DEBEN incluir soporte integrado para AppWidgets y exponer elementos de la interfaz de usuario para agregar, configurar, ver y eliminar AppWidgets directamente dentro del Lanzador. Los lanzadores alternativos PUEDEN omitir estos elementos de la interfaz de usuario; sin embargo, si se omiten, el implementador del dispositivo DEBE proporcionar una aplicación separada accesible desde el Iniciador que permita a los usuarios agregar, configurar, ver y eliminar AppWidgets.

3.8.2. Notificaciones

Android incluye API que permiten a los desarrolladores notificar a los usuarios sobre eventos notables [ Recursos, 17 ]. Los implementadores de dispositivos DEBEN brindar soporte para cada clase de notificación así definida; en concreto: sonidos, vibración, luz y barra de estado.

Además, la implementación DEBE representar correctamente todos los recursos (iconos, archivos de sonido, etc.) proporcionados en las API [ Recursos, 18 ], o en la guía de estilo de iconos de la barra de estado [ Recursos, 19 ]. Los implementadores de dispositivos PUEDEN proporcionar una experiencia de usuario alternativa para las notificaciones a la proporcionada por la implementación de código abierto de Android de referencia; sin embargo, dichos sistemas de notificación alternativos DEBEN respaldar los recursos de notificación existentes, como se indicó anteriormente.

3.8.3. Buscar

Android incluye API [ Recursos, 20 ] que permiten a los desarrolladores incorporar búsquedas en sus aplicaciones y exponer los datos de sus aplicaciones en la búsqueda global del sistema. Generally speaking, this functionality consists of a single, system-wide user interface that allows users to enter queries, displays suggestions as users type, and displays results. The Android APIs allow developers to reuse this interface to provide search within their own apps, and allow developers to supply results to the common global search user interface.

Device implementations MUST include a single, shared, system-wide search user interface capable of real-time suggestions in response to user input. Device implementations MUST implement the APIs that allow developers to reuse this user interface to provide search within their own applications. Device implementations MUST implement the APIs that allow third-party applications to add suggestions to the search box when it is run in global search mode. If no third-party applications are installed that make use of this functionality, the default behavior SHOULD be to display web search engine results and suggestions.

Device implementations MAY ship alternate search user interfaces, but SHOULD include a hard or soft dedicated search button, that can be used at any time within any app to invoke the search framework, with the behavior provided for in the API documentation.

3.8.4. Toasts

Applications can use the "Toast" API (defined in [ Resources, 21 ]) to display short non-modal strings to the end user, that disappear after a brief period of time. Device implementations MUST display Toasts from applications to end users in some high-visibility manner.

3.8.5. Live Wallpapers

Android defines a component type and corresponding API and lifecycle that allows applications to expose one or more "Live Wallpapers" to the end user [ Resources, 22 ]. Live Wallpapers are animations, patterns, or similar images with limited input capabilities that display as a wallpaper, behind other applications.

Hardware is considered capable of reliably running live wallpapers if it can run all live wallpapers, with no limitations on functionality, at a reasonable framerate with no adverse affects on other applications. If limitations in the hardware cause wallpapers and/or applications to crash, malfunction, consume excessive CPU or battery power, or run at unacceptably low frame rates, the hardware is considered incapable of running live wallpaper. As an example, some live wallpapers may use an Open GL 1.0 or 2.0 context to render their content. Live wallpaper will not run reliably on hardware that does not support multiple OpenGL contexts because the live wallpaper use of an OpenGL context may conflict with other applications that also use an OpenGL context.

Device implementations capable of running live wallpapers reliably as described above SHOULD implement live wallpapers. Device implementations determined to not run live wallpapers reliably as described above MUST NOT implement live wallpapers.

4. Application Packaging Compatibility

Device implementations MUST install and run Android ".apk" files as generated by the "aapt" tool included in the official Android SDK [ Resources, 23 ].

Devices implementations MUST NOT extend either the .apk [ Resources, 24 ], Android Manifest [ Resources, 25 ], or Dalvik bytecode [ Resources, 15 ] formats in such a way that would prevent those files from installing and running correctly on other compatible devices. Device implementers SHOULD use the reference upstream implementation of Dalvik, and the reference implementation's package management system.

5. Multimedia Compatibility

Device implementations MUST fully implement all multimedia APIs. Device implementations MUST include support for all multimedia codecs described below, and SHOULD meet the sound processing guidelines described below. Device implementations MUST include at least one form of audio output, such as speakers, headphone jack, external speaker connection, etc.

5.1. Media Codecs

Device implementations MUST support the multimedia codecs as detailed in the following sections. All of these codecs are provided as software implementations in the preferred Android implementation from the Android Open-Source Project.

Please note that neither Google nor the Open Handset Alliance make any representation that these codecs are unencumbered by third-party patents. Those intending to use this source code in hardware or software products are advised that implementations of this code, including in open source software or shareware, may require patent licenses from the relevant patent holders.

The tables below do not list specific bitrate requirements for most video codecs. The reason for this is that in practice, current device hardware does not necessarily support bitrates that map exactly to the required bitrates specified by the relevant standards. Instead, device implementations SHOULD support the highest bitrate practical on the hardware, up to the limits defined by the specifications.

5.1.1. Media Decoders

Device implementations MUST include an implementation of a decoder for each codec and format described in the table below. Note that decoders for each of these media types are provided by the upstream Android Open-Source Project.

5.1.2. Media Encoders

Device implementations SHOULD include encoders for as many of the media formats listed in Section 5.1.1. as possible. However, some encoders do not make sense for devices that lack certain optional hardware; for instance, an encoder for the H.263 video does not make sense, if the device lacks any cameras. Device implementations MUST therefore implement media encoders according to the conditions described in the table below.

See Section 7 for details on the conditions under which hardware may be omitted by device implementations.

In addition to the encoders listed above, device implementations SHOULD include an H.264 encoder. Note that the Compatibility Definition for a future version is planned to change this requirement to "MUST". That is, H.264 encoding is optional in Android 2.3 but will be required by a future version. Existing and new devices that run Android 2.3 are very strongly encouraged to meet this requirement in Android 2.3 , or they will not be able to attain Android compatibility when upgraded to the future version.

5.2. Audio Recording

When an application has used the android.media.AudioRecord API to start recording an audio stream, device implementations SHOULD sample and record audio with each of these behaviors:

• Noise reduction processing, if present, SHOULD be disabled.
• Automatic gain control, if present, SHOULD be disabled.
• The device SHOULD exhibit approximately flat amplitude versus frequency characteristics; specifically, ±3 dB, from 100 Hz to 4000 Hz
• Audio input sensitivity SHOULD be set such that a 90 dB sound power level (SPL) source at 1000 Hz yields RMS of 5000 for 16-bit samples.
• PCM amplitude levels SHOULD linearly track input SPL changes over at least a 30 dB range from -18 dB to +12 dB re 90 dB SPL at the microphone.
• Total harmonic distortion SHOULD be less than 1% from 100 Hz to 4000 Hz at 90 dB SPL input level.

Note: while the requirements outlined above are stated as "SHOULD" for Android 2.3, the Compatibility Definition for a future version is planned to change these to "MUST". That is, these requirements are optional in Android 2.3 but will be required by a future version. Existing and new devices that run Android 2.3 are very strongly encouraged to meet these requirements in Android 2.3 , or they will not be able to attain Android compatibility when upgraded to the future version.

5.3. Audio Latency

Audio latency is broadly defined as the interval between when an application requests an audio playback or record operation, and when the device implementation actually begins the operation. Many classes of applications rely on short latencies, to achieve real-time effects such sound effects or VOIP communication. Device implementations that include microphone hardware and declare android.hardware.microphone SHOULD meet all audio latency requirements outlined in this section. See Section 7 for details on the conditions under which microphone hardware may be omitted by device implementations.

For the purposes of this section:

• "cold output latency" is defined to be the interval between when an application requests audio playback and when sound begins playing, when the audio system has been idle and powered down prior to the request
• "warm output latency" is defined to be the interval between when an application requests audio playback and when sound begins playing, when the audio system has been recently used but is currently idle (that is, silent)
• "continuous output latency" is defined to be the interval between when an application issues a sample to be played and when the speaker physically plays the corresponding sound, while the device is currently playing back audio
• "cold input latency" is defined to be the interval between when an application requests audio recording and when the first sample is delivered to the application via its callback, when the audio system and microphone has been idle and powered down prior to the request
• "continuous input latency" is defined to be when an ambient sound occurs and when the sample corresponding to that sound is delivered to a recording application via its callback, while the device is in recording mode

Using the above definitions, device implementations SHOULD exhibit each of these properties:

• cold output latency of 100 milliseconds or less
• warm output latency of 10 milliseconds or less
• continuous output latency of 45 milliseconds or less
• cold input latency of 100 milliseconds or less
• continuous input latency of 50 milliseconds or less

Note: while the requirements outlined above are stated as "SHOULD" for Android 2.3, the Compatibility Definition for a future version is planned to change these to "MUST". That is, these requirements are optional in Android 2.3 but will be required by a future version. Existing and new devices that run Android 2.3 are very strongly encouraged to meet these requirements in Android 2.3 , or they will not be able to attain Android compatibility when upgraded to the future version.

If a device implementation meets the requirements of this section, it MAY report support for low-latency audio, by reporting the feature "android.hardware.audio.low-latency" via the android.content.pm.PackageManager class. [ Resources, 27 ] Conversely, if the device implementation does not meet these requirements it MUST NOT report support for low-latency audio.

6. Developer Tool Compatibility

Device implementations MUST support the Android Developer Tools provided in the Android SDK. Specifically, Android-compatible devices MUST be compatible with:

• Android Debug Bridge (known as adb) [ Resources, 23 ]
  Device implementations MUST support all adb functions as documented in the Android SDK. The device-side adb daemon SHOULD be inactive by default, but there MUST be a user-accessible mechanism to turn on the Android Debug Bridge.
• Dalvik Debug Monitor Service (known as ddms) [ Resources, 23 ]
  Device implementations MUST support all ddms features as documented in the Android SDK. As ddms uses adb , support for ddms SHOULD be inactive by default, but MUST be supported whenever the user has activated the Android Debug Bridge, as above.
• Monkey [ Resources, 26 ]
  Device implementations MUST include the Monkey framework, and make it available for applications to use.

Most Linux-based systems and Apple Macintosh systems recognize Android devices using the standard Android SDK tools, without additional support; however Microsoft Windows systems typically require a driver for new Android devices. (For instance, new vendor IDs and sometimes new device IDs require custom USB drivers for Windows systems.) If a device implementation is unrecognized by the adb tool as provided in the standard Android SDK, device implementers MUST provide Windows drivers allowing developers to connect to the device using the adb protocol. These drivers MUST be provided for Windows XP, Windows Vista, and Windows 7, in both 32-bit and 64-bit versions.

7. Hardware Compatibility

Android is intended to enable device implementers to create innovative form factors and configurations. At the same time Android developers write innovative applications that rely on the various hardware and features available through the Android APIs. The requirements in this section strike a balance between innovations available to device implementers, and the needs of developers to ensure their apps are only available to devices where they will run properly.

If a device includes a particular hardware component that has a corresponding API for third-party developers, the device implementation MUST implement that API as described in the Android SDK documentation. If an API in the SDK interacts with a hardware component that is stated to be optional and the device implementation does not possess that component:

• complete class definitions (as documented by the SDK) for the component's APIs MUST still be present
• the API's behaviors MUST be implemented as no-ops in some reasonable fashion
• API methods MUST return null values where permitted by the SDK documentation
• API methods MUST return no-op implementations of classes where null values are not permitted by the SDK documentation
• API methods MUST NOT throw exceptions not documented by the SDK documentation

A typical example of a scenario where these requirements apply is the telephony API: even on non-phone devices, these APIs must be implemented as reasonable no-ops.

Device implementations MUST accurately report accurate hardware configuration information via the getSystemAvailableFeatures() and hasSystemFeature(String) methods on the android.content.pm.PackageManager class. [ Resources, 27 ]

7.1. Display and Graphics

Android 2.3 includes facilities that automatically adjust application assets and UI layouts appropriately for the device, to ensure that third-party applications run well on a variety of hardware configurations [ Resources, 28 ]. Devices MUST properly implement these APIs and behaviors, as detailed in this section.

7.1.1. Screen Configurations

Device implementations MAY use screens of any pixel dimensions, provided that they meet the following requirements:

• screens MUST be at least 2.5 inches in physical diagonal size
• density MUST be at least 100 dpi
• the aspect ratio MUST be between 1.333 (4:3) and 1.779 (16:9)
• the display technology used consists of square pixels

Device implementations with a screen meeting the requirements above are considered compatible, and no additional action is necessary. The Android framework implementation automatically computes display characteristics such as screen size bucket and density bucket. In the majority of cases, the framework decisions are the correct ones. If the default framework computations are used, no additional action is necessary. Device implementers wishing to change the defaults, or use a screen that does not meet the requirements above MUST contact the Android Compatibility Team for guidance, as provided for in Section 12.

The units used by the requirements above are defined as follows:

• "Physical diagonal size" is the distance in inches between two opposing corners of the illuminated portion of the display.
• "dpi" (meaning "dots per inch") is the number of pixels encompassed by a linear horizontal or vertical span of 1". Where dpi values are listed, both horizontal and vertical dpi must fall within the range.
• "Aspect ratio" is the ratio of the longer dimension of the screen to the shorter dimension. For example, a display of 480x854 pixels would be 854 / 480 = 1.779, or roughly "16:9".

Device implementations MUST use only displays with a single static configuration. That is, device implementations MUST NOT enable multiple screen configurations. For instance, since a typical television supports multiple resolutions such as 1080p, 720p, and so on, this configuration is not compatible with Android 2.3. (However, support for such configurations is under investigation and planned for a future version of Android.)

7.1.2. Display Metrics

Device implementations MUST report correct values for all display metrics defined in android.util.DisplayMetrics [ Resources, 29 ].

7.1.3. Declared Screen Support

Applications optionally indicate which screen sizes they support via the <supports-screens> attribute in the AndroidManifest.xml file. Device implementations MUST correctly honor applications' stated support for small, medium, and large screens, as described in the Android SDK documentation.

7.1.4. Screen Orientation

Compatible devices MUST support dynamic orientation by applications to either portrait or landscape screen orientation. That is, the device must respect the application's request for a specific screen orientation. Device implementations MAY select either portrait or landscape orientation as the default. Devices that cannot be physically rotated MAY meet this requirement by "letterboxing" applications that request portrait mode, using only a portion of the available display.

Devices MUST report the correct value for the device's current orientation, whenever queried via the android.content.res.Configuration.orientation, android.view.Display.getOrientation(), or other APIs.

7.1.5. 3D Graphics Acceleration

Device implementations MUST support OpenGL ES 1.0, as required by the Android 2.3 APIs. For devices that lack 3D acceleration hardware, a software implementation of OpenGL ES 1.0 is provided by the upstream Android Open-Source Project. Device implementations SHOULD support OpenGL ES 2.0.

Implementations MAY omit Open GL ES 2.0 support; however if support is omitted, device implementations MUST NOT report as supporting OpenGL ES 2.0. Specifically, if a device implementations lacks OpenGL ES 2.0 support:

• the managed APIs (such as via the GLES10.getString() method) MUST NOT report support for OpenGL ES 2.0
• the native C/C++ OpenGL APIs (that is, those available to apps via libGLES_v1CM.so, libGLES_v2.so, or libEGL.so) MUST NOT report support for OpenGL ES 2.0.

Conversely, if a device implementation does support OpenGL ES 2.0, it MUST accurately report that support via the routes just listed.

Note that Android 2.3 includes support for applications to optionally specify that they require specific OpenGL texture compression formats. These formats are typically vendor-specific. Device implementations are not required by Android 2.3 to implement any specific texture compression format. However, they SHOULD accurately report any texture compression formats that they do support, via the getString() method in the OpenGL API.

7.2. Input Devices

Android 2.3 supports a number of modalities for user input. Device implementations MUST support user input devices as provided for in this section.

7.2.1. Keyboard

Device implementations:

• MUST include support for the Input Management Framework (which allows third party developers to create Input Management Engines -- ie soft keyboard) as detailed at developer.android.com
• MUST provide at least one soft keyboard implementation (regardless of whether a hard keyboard is present)
• MAY include additional soft keyboard implementations
• MAY include a hardware keyboard
• MUST NOT include a hardware keyboard that does not match one of the formats specified in android.content.res.Configuration.keyboard [ Resources, 30 ] (that is, QWERTY, or 12-key)

7.2.2. Non-touch Navigation

Device implementations:

• MAY omit a non-touch navigation option (that is, may omit a trackball, d-pad, or wheel)
• MUST report the correct value for android.content.res.Configuration.navigation [ Resources, 30 ]
• MUST provide a reasonable alternative user interface mechanism for the selection and editing of text, compatible with Input Management Engines. The upstream Android Open-Source code includes a selection mechanism suitable for use with devices that lack non-touch navigation inputs.

7.2.3. Navigation keys

The Home, Menu and Back functions are essential to the Android navigation paradigm. Device implementations MUST make these functions available to the user at all times, regardless of application state. These functions SHOULD be implemented via dedicated buttons. They MAY be implemented using software, gestures, touch panel, etc., but if so they MUST be always accessible and not obscure or interfere with the available application display area.

Device implementers SHOULD also provide a dedicated search key. Device implementers MAY also provide send and end keys for phone calls.

7.2.4. Touchscreen input

Device implementations:

• MUST have a touchscreen
• MAY have either capacitive or resistive touchscreen
• MUST report the value of android.content.res.Configuration [ Resources, 30 ] reflecting corresponding to the type of the specific touchscreen on the device
• SHOULD support fully independently tracked pointers, if the touchscreen supports multiple pointers

7.3. Sensors

Android 2.3 includes APIs for accessing a variety of sensor types. Devices implementations generally MAY omit these sensors, as provided for in the following subsections. If a device includes a particular sensor type that has a corresponding API for third-party developers, the device implementation MUST implement that API as described in the Android SDK documentation. For example, device implementations:

• MUST accurately report the presence or absence of sensors per the android.content.pm.PackageManager class. [ Resources, 27 ]
• MUST return an accurate list of supported sensors via the SensorManager.getSensorList() and similar methods
• MUST behave reasonably for all other sensor APIs (for example, by returning true or false as appropriate when applications attempt to register listeners, not calling sensor listeners when the corresponding sensors are not present; etc.)

The list above is not comprehensive; the documented behavior of the Android SDK is to be considered authoritative.

Some sensor types are synthetic, meaning they can be derived from data provided by one or more other sensors. (Examples include the orientation sensor, and the linear acceleration sensor.) Device implementations SHOULD implement these sensor types, when they include the prerequisite physical sensors.

The Android 2.3 APIs introduce a notion of a "streaming" sensor, which is one that returns data continuously, rather than only when the data changes. Device implementations MUST continuously provide periodic data samples for any API indicated by the Android 2.3 SDK documentation to be a streaming sensor.

7.3.1. Accelerometer

Device implementations SHOULD include a 3-axis accelerometer. If a device implementation does include a 3-axis accelerometer, it:

• MUST be able to deliver events at 50 Hz or greater
• MUST comply with the Android sensor coordinate system as detailed in the Android APIs (see [ Resources, 31 ])
• MUST be capable of measuring from freefall up to twice gravity (2g) or more on any three-dimensional vector
• MUST have 8-bits of accuracy or more
• MUST have a standard deviation no greater than 0.05 m/s^2

7.3.2. Magnetometer

Device implementations SHOULD include a 3-axis magnetometer (ie compass.) If a device does include a 3-axis magnetometer, it:

• MUST be able to deliver events at 10 Hz or greater
• MUST comply with the Android sensor coordinate system as detailed in the Android APIs (see [ Resources, 31 ]).
• MUST be capable of sampling a range of field strengths adequate to cover the geomagnetic field
• MUST have 8-bits of accuracy or more
• MUST have a standard deviation no greater than 0.5 µT

7.3.3. GPS

Device implementations SHOULD include a GPS receiver. If a device implementation does include a GPS receiver, it SHOULD include some form of "assisted GPS" technique to minimize GPS lock-on time.

7.3.4. Gyroscope

Device implementations SHOULD include a gyroscope (ie angular change sensor.) Devices SHOULD NOT include a gyroscope sensor unless a 3-axis accelerometer is also included. If a device implementation includes a gyroscope, it:

• MUST be capable of measuring orientation changes up to 5.5*Pi radians/second (that is, approximately 1,000 degrees per second)
• MUST be able to deliver events at 100 Hz or greater
• MUST have 8-bits of accuracy or more

7.3.5. Barometer

Device implementations MAY include a barometer (ie ambient air pressure sensor.) If a device implementation includes a barometer, it:

• MUST be able to deliver events at 5 Hz or greater
• MUST have adequate precision to enable estimating altitude

7.3.7. Thermometer

Device implementations MAY but SHOULD NOT include a thermometer (ie temperature sensor.) If a device implementation does include a thermometer, it MUST measure the temperature of the device CPU. It MUST NOT measure any other temperature. (Note that this sensor type is deprecated in the Android 2.3 APIs.)

7.3.7. Photometer

Device implementations MAY include a photometer (ie ambient light sensor.)

7.3.8. Proximity Sensor

Device implementations MAY include a proximity sensor. If a device implementation does include a proximity sensor, it MUST measure the proximity of an object in the same direction as the screen. That is, the proximity sensor MUST be oriented to detect objects close to the screen, as the primary intent of this sensor type is to detect a phone in use by the user. If a device implementation includes a proximity sensor with any other orientation, it MUST NOT be accessible through this API. If a device implementation has a proximity sensor, it MUST be have 1-bit of accuracy or more.

7.4. Data Connectivity

Network connectivity and access to the Internet are vital features of Android. Meanwhile, device-to-device interaction adds significant value to Android devices and applications. Device implementations MUST meet the data connectivity requirements in this section.

7.4.1. Telephony

"Telephony" as used by the Android 2.3 APIs and this document refers specifically to hardware related to placing voice calls and sending SMS messages via a GSM or CDMA network. While these voice calls may or may not be packet-switched, they are for the purposes of Android 2.3 considered independent of any data connectivity that may be implemented using the same network. In other words, the Android "telephony" functionality and APIs refer specifically to voice calls and SMS; for instance, device implementations that cannot place calls or send/receive SMS messages MUST NOT report the "android.hardware.telephony" feature or any sub-features, regardless of whether they use a cellular network for data connectivity.

Android 2.3 MAY be used on devices that do not include telephony hardware. That is, Android 2.3 is compatible with devices that are not phones. However, if a device implementation does include GSM or CDMA telephony, it MUST implement full support for the API for that technology. Device implementations that do not include telephony hardware MUST implement the full APIs as no-ops.

7.4.2. IEEE 802.11 (WiFi)

Android 2.3 device implementations SHOULD include support for one or more forms of 802.11 (b/g/a/n, etc.) If a device implementation does include support for 802.11, it MUST implement the corresponding Android API.

7.4.3. Bluetooth

Device implementations SHOULD include a Bluetooth transceiver. Device implementations that do include a Bluetooth transceiver MUST enable the RFCOMM-based Bluetooth API as described in the SDK documentation [ Resources, 32 ]. Device implementations SHOULD implement relevant Bluetooth profiles, such as A2DP, AVRCP, OBEX, etc. as appropriate for the device.

The Compatibility Test Suite includes cases that cover basic operation of the Android RFCOMM Bluetooth API. However, since Bluetooth is a communications protocol between devices, it cannot be fully tested by unit tests running on a single device. Consequently, device implementations MUST also pass the human-driven Bluetooth test procedure described in Appendix A.

7.4.4. Near-Field Communications

Device implementations SHOULD include a transceiver and related hardware for Near-Field Communications (NFC). If a device implementation does include NFC hardware, then it:

• MUST report the android.hardware.nfc feature from the android.content.pm.PackageManager.hasSystemFeature() method. [ Resources, 27 ]
• MUST be capable of reading and writing NDEF messages via the following NFC standards:
  • MUST be capable of acting as an NFC Forum reader/writer (as defined by the NFC Forum technical specification NFCForum-TS-DigitalProtocol-1.0) via the following NFC standards:
    • NfcA (ISO14443-3A)
    • NfcB (ISO14443-3B)
    • NfcF (JIS 6319-4)
    • NfcV (ISO 15693)
    • IsoDep (ISO 14443-4)
    • NFC Forum Tag Types 1, 2, 3, 4 (defined by the NFC Forum)
  • MUST be capable of transmitting and receiving data via the following peer-to-peer standards and protocols:
    • ISO 18092
    • LLCP 1.0 (defined by the NFC Forum)
    • SDP 1.0 (defined by the NFC Forum)
    • NDEF Push Protocol [ Resources, 33 ]
  • MUST scan for all supported technologies while in NFC discovery mode.
  • SHOULD be in NFC discovery mode while the device is awake with the screen active.

  (Note that publicly available links are not available for the JIS, ISO, and NFC Forum specifications cited above.)

  Additionally, device implementations SHOULD support the following widely-deployed MIFARE technologies.

  • MIFARE Classic (NXP MF1S503x [ Resources, 34 ], MF1S703x [ Resources, 35 ])
  • MIFARE Ultralight (NXP MF0ICU1 [ Resources, 36 ], MF0ICU2 [ Resources, 37 ])
  • NDEF on MIFARE Classic (NXP AN130511 [ Resources, 38 ], AN130411 [ Resources, 39 ])

  Note that Android 2.3.3 includes APIs for these MIFARE types. If a device implementation supports MIFARE, it:

  • MUST implement the corresponding Android APIs as documented by the Android SDK
  • MUST report the feature com.nxp.mifare from the android.content.pm.PackageManager.hasSystemFeature() method. [ Resources, 27 ] Note that this is not a standard Android feature, and as such does not appear as a constant on the PackageManager class.
  • MUST NOT implement the corresponding Android APIs nor report the com.nxp.mifare feature unless it also implements general NFC support as described in this section

  If a device implementation does not include NFC hardware, it MUST NOT declare the android.hardware.nfc feature from the android.content.pm.PackageManager.hasSystemFeature() method [ Resources, 27 ], and MUST implement the Android 2.3 NFC API as a no-op.

  As the classes android.nfc.NdefMessage and android.nfc.NdefRecord represent a protocol-independent data representation format, device implementations MUST implement these APIs even if they do not include support for NFC or declare the android.hardware.nfc feature.

  7.4.5. Minimum Network Capability

  Device implementations MUST include support for one or more forms of data networking. Specifically, device implementations MUST include support for at least one data standard capable of 200Kbit/sec or greater. Examples of technologies that satisfy this requirement include EDGE, HSPA, EV-DO, 802.11g, Ethernet, etc.

  Device implementations where a physical networking standard (such as Ethernet) is the primary data connection SHOULD also include support for at least one common wireless data standard, such as 802.11 (WiFi).

  Devices MAY implement more than one form of data connectivity.

  7.5. Cameras

  Device implementations SHOULD include a rear-facing camera, and MAY include a front-facing camera. A rear-facing camera is a camera located on the side of the device opposite the display; that is, it images scenes on the far side of the device, like a traditional camera. A front-facing camera is a camera located on the same side of the device as the display; that is, a camera typically used to image the user, such as for video conferencing and similar applications.

  7.5.1. Rear-Facing Camera

  Device implementations SHOULD include a rear-facing camera. If a device implementation includes a rear-facing camera, it:

  • MUST have a resolution of at least 2 megapixels
  • SHOULD have either hardware auto-focus, or software auto-focus implemented in the camera driver (transparent to application software)
  • MAY have fixed-focus or EDOF (extended depth of field) hardware
  • MAY include a flash. If the Camera includes a flash, the flash lamp MUST NOT be lit while an android.hardware.Camera.PreviewCallback instance has been registered on a Camera preview surface, unless the application has explicitly enabled the flash by enabling the FLASH_MODE_AUTO or FLASH_MODE_ON attributes of a Camera.Parameters object. Note that this constraint does not apply to the device's built-in system camera application, but only to third-party applications using Camera.PreviewCallback .

  7.5.2. Front-Facing Camera

  Device implementations MAY include a front-facing camera. If a device implementation includes a front-facing camera, it:

  • MUST have a resolution of at least VGA (that is, 640x480 pixels)
  • MUST NOT use a front-facing camera as the default for the Camera API. That is, the camera API in Android 2.3 has specific support for front-facing cameras, and device implementations MUST NOT configure the API to to treat a front-facing camera as the default rear-facing camera, even if it is the only camera on the device.
  • MAY include features (such as auto-focus, flash, etc.) available to rear-facing cameras as described in Section 7.5.1.
  • MUST horizontally reflect (ie mirror) the stream displayed by an app in a CameraPreview, as follows:
  • If the device implementation is capable of being rotated by user (such as automatically via an accelerometer or manually via user input), the camera preview MUST be mirrored horizontally relative to the device's current orientation.
  • If the current application has explicitly requested that the Camera display be rotated via a call to the android.hardware.Camera.setDisplayOrientation() [ Resources, 40 ] method, the camera preview MUST be mirrored horizontally relative to the orientation specified by the application.
  • Otherwise, the preview MUST be mirrored along the device's default horizontal axis.
  • MUST mirror the image data returned to any "postview" camera callback handlers, in the same manner as the camera preview image stream. (If the device implementation does not support postview callbacks, this requirement obviously does not apply.)
  • MUST NOT mirror the final captured still image or video streams returned to application callbacks or committed to media storage

  7.5.3. Camera API Behavior

  Device implementations MUST implement the following behaviors for the camera-related APIs, for both front- and rear-facing cameras:

  1. If an application has never called android.hardware.Camera.Parameters.setPreviewFormat(int), then the device MUST use android.hardware.PixelFormat.YCbCr_420_SP for preview data provided to application callbacks.
  2. If an application registers an android.hardware.Camera.PreviewCallback instance and the system calls the onPreviewFrame() method when the preview format is YCbCr_420_SP, the data in the byte[] passed into onPreviewFrame() must further be in the NV21 encoding format. That is, NV21 MUST be the default.
  3. Device implementations SHOULD support the YV12 format (as denoted by the android.graphics.ImageFormat.YV12 constant) for camera previews for both front- and rear-facing cameras. Note that the Compatibility Definition for a future version is planned to change this requirement to "MUST". That is, YV12 support is optional in Android 2.3 but will be required by a future version. Existing and new devices that run Android 2.3 are very strongly encouraged to meet this requirement in Android 2.3 , or they will not be able to attain Android compatibility when upgraded to the future version.

  Device implementations MUST implement the full Camera API included in the Android 2.3 SDK documentation [ Resources, 41 ]), regardless of whether the device includes hardware autofocus or other capabilities. For instance, cameras that lack autofocus MUST still call any registered android.hardware.Camera.AutoFocusCallback instances (even though this has no relevance to a non-autofocus camera.) Note that this does apply to front-facing cameras; for instance, even though most front-facing cameras do not support autofocus, the API callbacks must still be "faked" as described.

  Device implementations MUST recognize and honor each parameter name defined as a constant on the android.hardware.Camera.Parameters class, if the underlying hardware supports the feature. If the device hardware does not support a feature, the API must behave as documented. Conversely, Device implementations MUST NOT honor or recognize string constants passed to the android.hardware.Camera.setParameters() method other than those documented as constants on the android.hardware.Camera.Parameters . That is, device implementations MUST support all standard Camera parameters if the hardware allows, and MUST NOT support custom Camera parameter types.

  7.5.4. Camera Orientation

  Both front- and rear-facing cameras, if present, MUST be oriented so that the long dimension of the camera aligns with the screen's long dimension. That is, when the device is held in the landscape orientation, a cameras MUST capture images in the landscape orientation. This applies regardless of the device's natural orientation; that is, it applies to landscape-primary devices as well as portrait-primary devices.

  7.6. Memory and Storage

  The fundamental function of Android 2.3 is to run applications. Device implementations MUST the requirements of this section, to ensure adequate storage and memory for applications to run properly.

  7.6.1. Minimum Memory and Storage

  Device implementations MUST have at least 128MB of memory available to the kernel and userspace. The 128MB MUST be in addition to any memory dedicated to hardware components such as radio, memory, and so on that is not under the kernel's control.

  Device implementations MUST have at least 150MB of non-volatile storage available for user data. That is, the /data partition MUST be at least 150MB.

  Beyond the requirements above, device implementations SHOULD have at least 1GB of non-volatile storage available for user data. Note that this higher requirement is planned to become a hard minimum in a future version of Android. Device implementations are strongly encouraged to meet these requirements now, or else they may not be eligible for compatibility for a future version of Android.

  The Android APIs include a Download Manager that applications may use to download data files. The Download Manager implementation MUST be capable of downloading individual files 55MB in size, or larger. The Download Manager implementation SHOULD be capable of downloading files 100MB in size, or larger.

  7.6.2. Application Shared Storage

  Device implementations MUST offer shared storage for applications. The shared storage provided MUST be at least 1GB in size.

  Device implementations MUST be configured with shared storage mounted by default, "out of the box". If the shared storage is not mounted on the Linux path /sdcard , then the device MUST include a Linux symbolic link from /sdcard to the actual mount point.

  Device implementations MUST enforce as documented the android.permission.WRITE_EXTERNAL_STORAGE permission on this shared storage. Shared storage MUST otherwise be writable by any application that obtains that permission.

  Device implementations MAY have hardware for user-accessible removable storage, such as a Secure Digital card. Alternatively, device implementations MAY allocate internal (non-removable) storage as shared storage for apps.

  Regardless of the form of shared storage used, device implementations MUST provide some mechanism to access the contents of shared storage from a host computer, such as USB mass storage or Media Transfer Protocol.

  It is illustrative to consider two common examples. If a device implementation includes an SD card slot to satisfy the shared storage requirement, a FAT-formatted SD card 1GB in size or larger MUST be included with the device as sold to users, and MUST be mounted by default. Alternatively, if a device implementation uses internal fixed storage to satisfy this requirement, that storage MUST be 1GB in size or larger and mounted on /sdcard (or /sdcard MUST be a symbolic link to the physical location if it is mounted elsewhere.)

  Device implementations that include multiple shared storage paths (such as both an SD card slot and shared internal storage) SHOULD modify the core applications such as the media scanner and ContentProvider to transparently support files placed in both locations.

  7.7. USB

  Device implementations:

  • MUST implement a USB client, connectable to a USB host with a standard USB-A port
  • MUST implement the Android Debug Bridge over USB (as described in Section 7)
  • MUST implement the USB mass storage specification, to allow a host connected to the device to access the contents of the /sdcard volume
  • SHOULD use the micro USB form factor on the device side
  • MAY include a non-standard port on the device side, but if so MUST ship with a cable capable of connecting the custom pinout to standard USB-A port

  8. Performance Compatibility

  Compatible implementations must ensure not only that applications simply run correctly on the device, but that they do so with reasonable performance and overall good user experience. Device implementations MUST meet the key performance metrics of an Android 2.3 compatible device defined in the table below:

  Metric	Performance Threshold	Comments
  Application Launch Time	The following applications should launch within the specified time. Browser: less than 1300ms MMS/SMS: less than 700ms AlarmClock: less than 650ms	The launch time is measured as the total time to complete loading the default activity for the application, including the time it takes to start the Linux process, load the Android package into the Dalvik VM, and call onCreate.
  Simultaneous Applications	When multiple applications have been launched, re-launching an already-running application after it has been launched must take less than the original launch time.

  9. Security Model Compatibility

  Device implementations MUST implement a security model consistent with the Android platform security model as defined in Security and Permissions reference document in the APIs [ Resources, 42 ] in the Android developer documentation. Device implementations MUST support installation of self-signed applications without requiring any additional permissions/certificates from any third parties/authorities. Specifically, compatible devices MUST support the security mechanisms described in the follow sub-sections.

  9.1. Permisos

  Device implementations MUST support the Android permissions model as defined in the Android developer documentation [ Resources, 42 ]. Specifically, implementations MUST enforce each permission defined as described in the SDK documentation; no permissions may be omitted, altered, or ignored. Implementations MAY add additional permissions, provided the new permission ID strings are not in the android.* namespace.

  9.2. UID and Process Isolation

  Device implementations MUST support the Android application sandbox model, in which each application runs as a unique Unix-style UID and in a separate process. Device implementations MUST support running multiple applications as the same Linux user ID, provided that the applications are properly signed and constructed, as defined in the Security and Permissions reference [ Resources, 42 ].

  9.3. Filesystem Permissions

  Device implementations MUST support the Android file access permissions model as defined in as defined in the Security and Permissions reference [ Resources, 42 ].

  9.4. Alternate Execution Environments

  Device implementations MAY include runtime environments that execute applications using some other software or technology than the Dalvik virtual machine or native code. However, such alternate execution environments MUST NOT compromise the Android security model or the security of installed Android applications, as described in this section.

  Alternate runtimes MUST themselves be Android applications, and abide by the standard Android security model, as described elsewhere in Section 9.

  Alternate runtimes MUST NOT be granted access to resources protected by permissions not requested in the runtime's AndroidManifest.xml file via the <uses-permission> mechanism.

  Alternate runtimes MUST NOT permit applications to make use of features protected by Android permissions restricted to system applications.

  Alternate runtimes MUST abide by the Android sandbox model. Specifically:

  • Alternate runtimes SHOULD install apps via the PackageManager into separate Android sandboxes (that is, Linux user IDs, etc.)
  • Alternate runtimes MAY provide a single Android sandbox shared by all applications using the alternate runtime.
  • Alternate runtimes and installed applications using an alternate runtime MUST NOT reuse the sandbox of any other app installed on the device, except through the standard Android mechanisms of shared user ID and signing certificate
  • Alternate runtimes MUST NOT launch with, grant, or be granted access to the sandboxes corresponding to other Android applications.

  Alternate runtimes MUST NOT be launched with, be granted, or grant to other applications any privileges of the superuser (root), or of any other user ID.

  The .apk files of alternate runtimes MAY be included in the system image of a device implementation, but MUST be signed with a key distinct from the key used to sign other applications included with the device implementation.

  When installing applications, alternate runtimes MUST obtain user consent for the Android permissions used by the application. That is, if an application needs to make use of a device resource for which there is a corresponding Android permission (such as Camera, GPS, etc.), the alternate runtime MUST inform the user that the application will be able to access that resource. If the runtime environment does not record application capabilities in this manner, the runtime environment MUST list all permissions held by the runtime itself when installing any application using that runtime.

  10. Software Compatibility Testing

  The Android Open-Source Project includes various testing tools to verify that device implementations are compatible. Device implementations MUST pass all tests described in this section.

  However, note that no software test package is fully comprehensive. For this reason, device implementers are very strongly encouraged to make the minimum number of changes as possible to the reference and preferred implementation of Android 2.3 available from the Android Open-Source Project. This will minimize the risk of introducing bugs that create incompatibilities requiring rework and potential device updates.

  10.1. Compatibility Test Suite

  Device implementations MUST pass the Android Compatibility Test Suite (CTS) [ Resources, 2 ] available from the Android Open Source Project, using the final shipping software on the device. Additionally, device implementers SHOULD use the reference implementation in the Android Open Source tree as much as possible, and MUST ensure compatibility in cases of ambiguity in CTS and for any reimplementations of parts of the reference source code.

  The CTS is designed to be run on an actual device. Like any software, the CTS may itself contain bugs. The CTS will be versioned independently of this Compatibility Definition, and multiple revisions of the CTS may be released for Android 2.3. Device implementations MUST pass the latest CTS version available at the time the device software is completed.

  MUST pass the most recent version of the Android Compatibility Test Suite (CTS) available at the time of the device implementation's software is completed. (The CTS is available as part of the Android Open Source Project [ Resources, 2 ].) The CTS tests many, but not all, of the components outlined in this document.

  10.2. CTS Verifier

  Device implementations MUST correctly execute all applicable cases in the CTS Verifier. The CTS Verifier is included with the Compatibility Test Suite, and is intended to be run by a human operator to test functionality that cannot be tested by an automated system, such as correct functioning of a camera and sensors.

  The CTS Verifier has tests for many kinds of hardware, including some hardware that is optional. Device implementations MUST pass all tests for hardware which they possess; for instance, if a device possesses an accelerometer, it MUST correctly execute the Accelerometer test case in the CTS Verifier. Test cases for features noted as optional by this Compatibility Definition Document MAY be skipped or omitted.

  Every device and every build MUST correctly run the CTS Verifier, as noted above. However, since many builds are very similar, device implementers are not expected to explicitly run the CTS Verifier on builds that differ only in trivial ways. Specifically, device implementations that differ from an implementation that has passed the CTS Verfier only by the set of included locales, branding, etc. MAY omit the CTS Verifier test.

  10.3. Reference Applications

  Device implementers MUST test implementation compatibility using the following open-source applications:

  • The "Apps for Android" applications [ Resources, 43 ].
  • Replica Island (available in Android Market; only required for device implementations that support with OpenGL ES 2.0)

  Each app above MUST launch and behave correctly on the implementation, for the implementation to be considered compatible.

  11. Updatable Software

  Device implementations MUST include a mechanism to replace the entirety of the system software. The mechanism need not perform "live" upgrades -- that is, a device restart MAY be required.

  Any method can be used, provided that it can replace the entirety of the software preinstalled on the device. For instance, any of the following approaches will satisfy this requirement:

  • Over-the-air (OTA) downloads with offline update via reboot
  • "Tethered" updates over USB from a host PC
  • "Offline" updates via a reboot and update from a file on removable storage

  The update mechanism used MUST support updates without wiping user data. Note that the upstream Android software includes an update mechanism that satisfies this requirement.

  If an error is found in a device implementation after it has been released but within its reasonable product lifetime that is determined in consultation with the Android Compatibility Team to affect the compatibility of third-party applications, the device implementer MUST correct the error via a software update available that can be applied per the mechanism just described.

  12. Contact Us

  You can contact the document authors at compatibility@android.com for clarifications and to bring up any issues that you think the document does not cover.

  Appendix A - Bluetooth Test Procedure

  The Compatibility Test Suite includes cases that cover basic operation of the Android RFCOMM Bluetooth API. However, since Bluetooth is a communications protocol between devices, it cannot be fully tested by unit tests running on a single device. Consequently, device implementations MUST also pass the human-operated Bluetooth test procedure described below.

  The test procedure is based on the BluetoothChat sample app included in the Android open-source project tree. The procedure requires two devices:

  • a candidate device implementation running the software build to be tested
  • a separate device implementation already known to be compatible, and of a model from the device implementation being tested -- that is, a "known good" device implementation

  The test procedure below refers to these devices as the "candidate" and "known good" devices, respectively.

  Setup and Installation

  1. Build BluetoothChat.apk via 'make samples' from an Android source code tree.
  2. Install BluetoothChat.apk on the known-good device.
  3. Install BluetoothChat.apk on the candidate device.

  Test Bluetooth Control by Apps

  1. Launch BluetoothChat on the candidate device, while Bluetooth is disabled.
  2. Verify that the candidate device either turns on Bluetooth, or prompts the user with a dialog to turn on Bluetooth.

  Test Pairing and Communication

  1. Launch the Bluetooth Chat app on both devices.
  2. Make the known-good device discoverable from within BluetoothChat (using the Menu).
  3. On the candidate device, scan for Bluetooth devices from within BluetoothChat (using the Menu) and pair with the known-good device.
  4. Send 10 or more messages from each device, and verify that the other device receives them correctly.
  5. Close the BluetoothChat app on both devices by pressing Home .
  6. Unpair each device from the other, using the device Settings app.

  Test Pairing and Communication in the Reverse Direction

  1. Launch the Bluetooth Chat app on both devices.
  2. Make the candidate device discoverable from within BluetoothChat (using the Menu).
  3. On the known-good device, scan for Bluetooth devices from within BluetoothChat (using the Menu) and pair with the candidate device.
  4. Send 10 or messages from each device, and verify that the other device receives them correctly.
  5. Close the Bluetooth Chat app on both devices by pressing Back repeatedly to get to the Launcher.

  Test Re-Launches

  1. Re-launch the Bluetooth Chat app on both devices.
  2. Send 10 or messages from each device, and verify that the other device receives them correctly.

  Note: the above tests have some cases which end a test section by using Home, and some using Back. These tests are not redundant and are not optional: the objective is to verify that the Bluetooth API and stack works correctly both when Activities are explicitly terminated (via the user pressing Back, which calls finish()), and implicitly sent to background (via the user pressing Home.) Each test sequence MUST be performed as described.